Solid dielectric capacitor and method of manufacture

ABSTRACT

A monolithic capacitor having a dielectric ceramic body cosintered with at least two base metal electrodes. The ceramic body is composed of a major ingredient expressed by the formula, 
     (1-α){(Ba k-x  M x )O k  TiO 2  }+αCaZrO 3   
     where M is either or both of calcium and strontium, and α, k and y are numerals in specified ranges. To this major ingredient is added a minor proportion of a mixture of lithium oxide, silicon dioxide and at least one metal oxide selected from among barium oxide, strontium oxide, calcium oxide, magnesium oxide and zinc oxide. For the fabrication of capacitors the mixture of the above major ingredients and additives in finely divided form are formed into moldings of desired shape and size, each with at least two electrodes buried therein. The moldings and electrodes are cosintered in a reductive or neutral atmosphere at temperatures of less than 1200° C. and then are reheated at a lower temperature in an oxidative atmosphere.

BACKGROUND OF THE INVENTION

Our invention relates to solid dielectric capacitors and moreparticularly to a monolithic ceramic capacitor comprising a single ormultiple layered ceramic body and at lest two electrodes in contacttherewith. The invention also pertains to a method of fabricating suchcapacitors.

Multilayered ceramic capacitors have long been known and usedextensively which employ noble metals such as platinum and palladium asthe electrode materials. Generally, for the fabrication of suchcapacitors, "green " (unsintered) dielectric sheets have first beenprepared from the proportioned ingredients of a desired dielectricceramic material in finely divided form. An electroconductive pastecontaining powdered platinum or palladium has then been "printed" on thegreen sheets in a desired pattern. Then a plurality of such printedgreen sheets have been stacked up, pressed together, and sintered in atemperature range of 1300° to 1600° C. in an oxidative atmosphere.

This conventional method makes possible the simultaneous firing(cosintering) of the dielectric ceramic layers and the film electrodesinterleaved therewith. It is also an acknowledged advantage of thisknown method that the noble metal electrodes are totally unaffected bythe high temperature sintering in an oxidative atmosphere. Offsettingall such advantages is the expensiveness of the noble metals, which addsubstantially to the manufacturing costs of the multilayered ceramiccapacitors.

Wada et al. U.S. Pat. No. 4,610,969, assigned to the assignee of theinstant application, suggests a solution to the above problem. Itteaches dielectric ceramic compositions consisting of a major ingredientexpressed by the formula, (Ba_(k-x) M_(x))O_(k) TiO₂, where M is atleast either of magnesium (Mg) and zinc (Zn), and additives consistingof lithium oxide (Li₂ O) and silicon dioxide (SiO₂). The compositionsmay, or may not, additionally include at least one metal oxide selectedfrom among barium oxide (BaO), calcium oxide (CaO) and strontium oxide(SrO).

Another solution is found in Wada et al. U.S. Pat. No. 4,610,970, whichproposes ceramic compositions whose major ingredient is expressed by theformula, (Ba_(k-x-y) M_(x) L_(y))O_(k) TiO₂, where M is at least eitherof Mg and Zn, and L is at least either of Sr and Ca. To this majoringredient are added Li₂ O, SiO₂, and, optionally, at least one othermetal oxide selected from among BaO, CaO and SrO.

Wada et al. U.S. Pat. No. 4,610,971 suggests still another solution,teaching use of a major ingredient expressed by the formula, (Ba_(k-x)M_(x))O_(k) TiO₂, where M is at least one of Mg, Zn, Sr and Ca. Thismajor ingredient is admixed with boric oxide (B₂ O₃), SiO₂ and,optionally, at least one other metal oxide selected from among BaO, MgO,ZnO, SrO and CaO.

A further solution is found in Wada et al. U.S. Pat. No. 4,610,968,which proposes ceramic compositions including a major ingredientexpressed by the formula, (Ba_(k-x) M_(x))O_(k) TiO₂, where M is atleast one of Mg, Zn, Sr and Ca. This major ingredient is admixed with B₂O₃ and at least one metal oxide selected from among BaO, MgO, ZnO, SrOand CaO.

All the foregoing known compositions make possible the fabrication ofceramic bodies by firing at temperature of not more than 1200° C. in anonoxidative (reductive or neutral) atmosphere. The ceramic bodies maytherefore be cosintered with electrodes of a base metal such as nickel.The resulting capacitors have specific dielectric constants of not lessthan 2000, and the temperature dependences of their capacitances arewithin plus or minus 10 percent in a temperature range of -25° to +85°C.

While these values are satisfactory for all practical purposes, we havenevertheless been hard pressed by our customers, with the recentdevelopment of microelectronics, for ceramic capacitors that have higherspecific dielectric constants with no less temperature dependences.

SUMMARY OF THE INVENTION

We have hereby invented how to manufacture ceramic capacitors that havehigher dielectric constants, with less temperature dependences over awide temperature range, than heretofore and which can be formed byfiring in a temperature range of not more than 1200° C. in anonoxidative atmosphere.

Briefly stated in one aspect thereof, our invention provides a soliddielectric capacitor of the above improved characteristics, comprising alow temperature sintered dielectric ceramic body and at least twoelectrodes in contact therewith. The ceramic body consists essentiallyof 100 parts by weight of a major ingredient that is expressed by theformula, (1-α){(Ba_(k-x) M_(x))O_(k) TiO₂ }+αCaZrO₃, and 0.2 to 5.0parts by weight of an additive mixture of Li₂ O, SiO₂ and at least oneof BaO, SrO, CaO, MgO and ZnO. In the formula of the major ingredient, Mis at least one of calcium and strontium, α is a numeral in the range of0.005 to 0.040, K is a numeral in the range of 1.00 to 1.05, and x is anumeral in the range of 0.01 to 0.05. The relative proportions of Li₂ O,SiO₂ and at least one selected metal oxide, altogether constituting theadditive mixture, will be specified with reference to he ternary diagramattached hereto.

Another aspect of our invention concerns a method of fabricating theceramic capacitor having the ceramic body of the above specifiedcomposition. The method dictates, first of all, the preparation of amixture of the above specified major ingredient and additives in finelydivided form. This mixture is then molded into a body of desired shapeand size, which is provided with at least two electrode portions of anelectroconductive material in any convenient manner. Then the moldingswith the electrode portions are cosintered in a reductive or neutralatmosphere and is subsequently reheated in an oxidative atmosphere.

The dielectric ceramic composition of our invention, set forth in theforegoing, makes it possible to sinter the moldings in a nonoxidativeatmosphere at temperatures not exceeding 1200° C. A preferredtemperature range for this molding operation is form 1050° to 1200° c.The sintering temperatures of less than 1200° C. enable the use ofnickel or like low cost base metal as the electrode material incosintering the ceramic boy and the electrodes.

Therefore, in the fabrication of ceramic capacitors by the method of ourinvention, an electroconductive paste of powdered nickel or like basemetal may be printed, coated, or otherwise formed on green sheets of thedielectric ceramic compositions in accordance with our invention. Thegreen sheets and the electroconductive layers thereon may be cosinteredat temperatures of not more than 1200° C.

The ceramic capacitors of our invention have proved to have veryfavorable physical and performance characteristics. The test capacitorsmanufactured in accordance with our invention, to be disclosedsubsequently, had specific dielectric constants of more than 3000,dielectric losses of not more than 2.5%, and resistivities of not lessthan 1×10⁶ megohm-centimeters. Also the temperature dependences of theirspecific dielectric constants were from -15% to +15% of the value at 25°C. in a temperature range of -55° to +125° C., and from -10% to +10 % ofthe value at 20° C. in a temperature range of -25° to +85° C.

The above and other features and advantages of our invention and themanner of realizing them will become more apparent, and the inventionitself will best be understood, from a study of the followingdescription and appended claims taken together with the attacheddrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a section through a monolithic, multilayered ceramic capacitorcapable of fabrication in accordance with the teachings of ourinvention, the illustrated capacitor being representative of numeroustest capacitors manufactured in the Examples of our invention to bepresented subsequently; and

FIG. 2 is a ternary diagram depicting the relative proportions of theadditives of the ceramic compositions in accordance with our invention.

DETAILED DESCRIPTION

We have illustrated in FIG. 1 one of many monolithic ceramic capacitorsof like construction fabricated in the subsequent Examples of ourinvention by way of a preferable embodiment thereof. Generallydesignated 10, the representative capacitor is shown to have aninterlamination of three dielectric ceramic layers 12 and two filmelectrodes 14. The three ceramic layers 12 constitute in combination asolid dielectric body 15 having the low temperature sinterable ceramiccompositions in accordance with our invention. The two film electrodes14, which can be of a low cost base metal such as nickel, extend fromboth sides of the dielectric body 15 toward, the terminate short of, theopposite sides of the dielectric body and so have an overlapping,parallel spaced relation to each other.

The capacitor 10 also includes a pair of conductive terminations 16which are formed on both sides of the dielectric body 15 and whichcontact the respective film electrodes 14. Each termination 16 is shownto comprise a baked on zinc layer 18, a plated on copper layer 20, and aplated on solder layer 22.

Typically, and as fabricated in the subsequent Examples of ourinvention, the intermediate one of the three dielectric layers 12 has athickness of 0.02 millimeter (mm). The area of that part of each filmelectrode 14 which overlaps the other film electrode is 25 mm² (5×5 mm).

EXAMPLES

We fabricated 75 different sets of test capacitors, each constructed asshown in FIG. 1, some having their dielectric bodies formulated inaccordance with the ceramic compositions of our invention and othersnot. Then we measured the specific dielectric constant, dielectric loss,resistivity, and temperature dependence of capacitance of the testcapacitors. Table 1 lists the compositions of the dielectric bodies ofall the test capacitors fabricated.

We have previously defined the major ingredient of the ceramiccompositions in accordance with our invention by the general formula,(1-α){(Ba_(k-x) M_(x))O_(k) TiO₂ }+α(CaZrO₃. Thus, in Table 1, we havegiven various combination of (1-α), α(k-x), x and k in the formula toindicate the specific major ingredients employed in the various Tests.The (1-α) and α indicate the relative proportions of (Ba_(k-x)M_(x))O_(k) TiO₂ and CaZrO₃ of the major ingredient in moles. The (k-x),x and k indicate the atomic numbers of the associated elements when theatomic number of Ti is one. Since M can be either or both of Ca and Sr,the column under x is subdivided into he atomic numbers of theseelements and their sum (x).

The ceramic compositions of our invention also includes a mixture of theadditives Li₂ O, SiO₂ and MO in various proportions. Table 1 specifiesthe amounts, in parts by weight, of the additive mixture with respect to100 parts by weight of the major ingredient, as well as the relativeproportions, in mole percent, of the additives Li₂ O, SiO₂ and MO.Further, since MO can be any one or more of BaO, MgO, ZnO, SrO and CaO,Table 1 gives the relative proportions, in mole percent, of these metaloxides.

                                      TABLE 1                                     __________________________________________________________________________    Ceramic Compositions                                                                                     Additives                                          Ingredient (100 wt. parts)      Composition                                   Test           x           Amount                                                                             (mole %) MO (mole %)                          No.                                                                              1 - α                                                                       α                                                                           k - x                                                                             Ca Sr Sum                                                                              k  (wt. part)                                                                         Li.sub.2 O                                                                       SiO.sub.2                                                                        MO BaO                                                                              SrO                                                                              CaO                                                                              MgO                                                                              ZnO                      __________________________________________________________________________     1 0.98                                                                              0.02                                                                              0.99                                                                              0.03                                                                             -- 0.03                                                                             1.02                                                                             2.0   1 80 19 20 -- 50 30 --                        2 "   "   "   "  -- "  "  "     1 39 60 "  -- "  "  --                        3 "   "   "   "  -- "  "  "    30 30 40 "  -- "  "  --                        4 "   "   "   "  -- "  "  "    50 50 -- -- -- -- -- --                        5 "   "   "   "  -- "  "  "    20 80 -- -- -- -- -- --                        6 "   "   "   "  -- "  "  "    10 50 40 20 -- 50 30 --                        7 "   "   "   "  -- "  "  "    30 40 30 "  -- "  "  --                        8 "   "   "   "  -- "  "  "    20 60 20 "  -- "  "  --                        9 "   "   "   "  -- "  "  "    35 65 -- -- -- -- -- --                       10 "   "   "   "  -- "  "  "     1 59 40 20 -- 50 30 --                       11 0.98                                                                              0.02                                                                               0.99                                                                             0.03                                                                             -- 0.03                                                                             1.02                                                                             2.0   1 85 14 20 -- 50 30 --                       12 "   "   "   "  -- "  "  "     1 29 70 "  -- "  "  --                       13 "   "   "   "  -- "  "  "    20 30 50 "  -- "  "  --                       14 "   "   "   "  -- "  "  "    50 30 20 "  -- "  "  --                       15 "   "   "   "  -- "  "  "    60 40 -- -- -- -- -- --                       16 "   "   "   "  -- "  "  "    10 90 -- -- -- -- -- --                       17 "   "   "   "  -- "  "  "    20 60 20 100                                                                              -- -- -- --                       18 "   "   "   "  -- "  "  "    "  "  "  -- 100                                                                              -- -- --                       19 "   "   "   "  -- "  "  "    "  "  "  -- -- 100                                                                              -- --                       20 "   "   "   "  -- "  "  "    "  "  "  -- -- -- 100                                                                              --                       21 0.98                                                                              0.02                                                                              0.99                                                                              0.03                                                                             -- 0.03                                                                             1.02                                                                             2.0  20 60 20 -- -- -- -- 100                      22 "   "   "   "  -- "  "  "    "  "  "  20 20 20 20 20                       23 "   "   "   "  -- "  "  "    "  "  "  40 10 20 10 20                       24 "   "   "   "  -- "  "  --   -- -- -- -- -- -- -- --                       25 "   "   "   "  -- "  "  0.2  15 75 10 30 10 10 30 20                       26 "   "   "   "  -- "  "  1.0  "  "  "  "  "  "  "  "                        27 "   "   "   "  -- "  "  3.0  "  "  "  "  "  "  "  "                        28 "   "   "   "  -- "  "  5.0  "  "  "  "  "  "  "  "                        29 "   "   "   "  -- "  "  7.0  "  "  "  "  "  "  "  "                        30  0.995                                                                             0.005                                                                            1.00                                                                              0.02                                                                             0.02                                                                             0.04                                                                             1.04                                                                             --   -- -- -- -- -- -- -- --                       31  0.995                                                                             0.005                                                                            1.00                                                                              0.02                                                                             0.02                                                                             0.04                                                                             1.04                                                                             0.2  15 40 45 20 20 20 20 20                       32 "   "   "   "  "  "  "  1.0  "  "  "  "  "  "  "  "                        33 "   "   "   "  "  "  "  3.0  "  "  "  "  "  "  "  "                        34 "   "   "   "  "  "  "  5.0  "  "  "  "  "  "  "  "                        35 "   "   "   "  "  "  "  7.0  "  "  "  "  "  "  "  "                        36 0.96                                                                              0.04                                                                              0.98                                                                              0.01                                                                             0.04                                                                             0.05                                                                             1.03                                                                             --   -- -- -- -- -- -- -- --                       37 "   "   "   "  "  "  "  0.2  30 40 30 -- 50 50 -- --                       38 "   "   "   "  "  "  "  1.0  "  "  "  -- "  "  -- --                       39 "   "   "   "  "  "  "  3.0  "  "  "  -- "  "  -- --                       40 "   "   "   "  "  "  "  5.0  "  "  "  -- "  "  -- --                       41 0.96                                                                              0.04                                                                              0.98                                                                              0.01                                                                             0.04                                                                             0.05                                                                             1.03                                                                             7.0  30 40 30 -- 50 50 -- --                       42 1.00                                                                              --  0.99                                                                              -- 0.02                                                                             0.02                                                                             1.01                                                                             3.0  10 50 40 20 20 20 20 20                       43  0.995                                                                             0.005                                                                            "   -- "  "  "  "    "  "  "  "  "  "  "  "                        44 0.98                                                                              0.02                                                                              "   -- "  "  "  "    "  "  "  "  "  "  "  "                        45 0.96                                                                              0.04                                                                              "   -- "  "  "  "    "  "  "  "  "  "  "  "                        46 0.95                                                                              0.05                                                                              "   -- "  "  "  "    "  "  "  "  "  "  "  "                        47 1.00                                                                              --  0.98                                                                              0.04                                                                             0.01                                                                             0.05                                                                             1.03                                                                             1.0  20 60 20 -- 100                                                                              -- -- --                       48  0.995                                                                             0.005                                                                            "   "  "  "  "  "    "  "  "  -- "  -- -- --                       49 0.98                                                                              0.02                                                                              "   "  "  "  "  "    "  "  "  -- "  -- -- --                       50 0.96                                                                              0.04                                                                              "   "  "  "  "  "    "  "  "  -- "  -- -- --                       51 0.95                                                                              0.05                                                                              0.98                                                                              0.04                                                                             0.01                                                                             0.05                                                                             1.03                                                                             1.0  20 60 20 -- 100                                                                              -- -- --                       52 0.98                                                                              0.02                                                                              1.00                                                                              -- -- -- 1.00                                                                             0.5  30 40 30 -- -- -- 100                                                                              --                       53 "   "   0.99                                                                              0.01                                                                             -- 0.01                                                                             "  "    "  "  "  -- -- -- "  --                       54 "   "   0.99                                                                              -- 0.01                                                                             0.01                                                                             "  "    "  "  "  -- -- -- "  --                       55 "   "   0.97                                                                              0.01                                                                             0.02                                                                             0.03                                                                             "  "    "  "  "  -- -- -- "  --                       56 "   "   0.95                                                                              0.05                                                                             -- 0.05                                                                             "  "    "  "  "  -- -- -- "  --                       57 "   "   0.95                                                                              -- 0.05                                                                             0.05                                                                             "  "    "  "  "  -- -- -- "  --                       58 "   "   0.93                                                                              0.07                                                                             -- 0.07                                                                             "  "    "  "  "  -- -- -- "  --                       59 "   "   0.93                                                                              -- 0.07                                                                             0.07                                                                             "  "    "  "  "  -- -- -- "  --                       60 0.97                                                                              0.03                                                                              1.05                                                                              -- -- -- 1.05                                                                             3.0  35 55 10 100                                                                              -- -- -- --                       61 0.97                                                                              0.03                                                                              1.04                                                                              0.01                                                                             -- 0.01                                                                             1.05                                                                             3.0  35 55 10 100                                                                              -- -- -- --                       62 "   "   1.04                                                                              -- 0.01                                                                             0.01                                                                             "  "    "  "  "  "  -- -- -- --                       63 "   "   1.02                                                                              0.02                                                                             0.01                                                                             0.03                                                                             "  "    "  "  "  "  -- -- -- --                       64 "   "   1.00                                                                              0.03                                                                             0.02                                                                             0.05                                                                             "  "    "  "  "  "  -- -- -- --                       65 "   "   0.98                                                                              0.05                                                                             0.02                                                                             0.07                                                                             "  "    "  "  "  "  -- -- -- --                       66 0.98                                                                              0.02                                                                              0.95                                                                              -- 0.03                                                                             0.03                                                                             0.98                                                                             1.0  10 50 40 20 20 20 20 20                       67 "   "   0.97                                                                              -- "  "  1.00                                                                             "    "  "  "  "  "  "  "  "                        68 "   "   1.00                                                                              -- "  "  1.03                                                                             "    "  "  "  "  "  "  "  "                        69 "   "   1.02                                                                              -- "  "  1.05                                                                             "    "  "  "  "  "  "  "  "                        70 "   "   1.04                                                                              -- "  "  1.07                                                                             "    "  "  "  "  "  "  "  "                        71 0.99                                                                              0.01                                                                              0.93                                                                              0.03                                                                             0.02                                                                             0.05                                                                             0.98                                                                             2.0  15 75 10 -- -- 100                                                                              -- --                       72 "   "   0.95                                                                              "  "  "  1.00                                                                             "    "  "  "  -- -- "  -- --                       73 "   "   0.98                                                                              "  "  "  1.03                                                                             "    "  "  "  -- -- "  -- --                       74 "   "   1.00                                                                              "  "  "  1.05                                                                             "    "  "  "  -- -- "  -- --                       75 "   "   1.02                                                                              "  "  "  1.07                                                                             "    "  "  "  -- -- "  -- --                       __________________________________________________________________________

According to Table 1, the major ingredient of the dielectric bodies ofthe capacitors of Test No. 1 was:

    0.98{(Ba.sub.0.99 Ca.sub.0.03)O.sub.1.02 TiO.sub.2 }+0.02CaZrO.sub.3,

or, more specifically, since M₀.03 =Ca₀.03,

    0.98{(BA.sub.0.99 Ca.sub.0.03)O.sub.1.02 TiO.sub.2 }+0.02CaZrO.sub.3.

One hundred parts by weight of this major ingredient was admixed with2.0 parts by weight of an additive minute of one mole percent Li₂ O, 80mole percent SiO₂ and 19 mole percent MO. The MO was a mixture of 20mole percent BaO, 50 mole percent CaO and 30 mole percent MgO.

For the fabrication of the capacitors of Test No. 1 we started with thepreparation of the first component, (Ba₀.99 Ca₀.03)O₁.02 TiO₂, of themajor ingredient. We prepared the following start materials for thefirst component of the major ingredient:

Barium carbonate (BaCO₃):

1053.12 grams (0.99 mole part)

Calcium carbonate (CaCO₃):

16.19 grams (0.03 mole part)

Titanium oxide (TiO₂):

430.70 grams (1.00 mole part)

These start materials had all purities of not less than 99.0 percent.The above specified weights of the start materials did not include thoseof the impurities contained.

We charged the start materials into a pot mill together with aluminaballs and 2.5 liters of water and intimately intermingled them bystirring the pot mill for 15 hours. Then we introduced the mixture intoa stainless steel pot and dried it by air heated to 150° C. for fourhours. Then we crushed the dried mixture into relatively coarseparticles and then fired the particles in air within a tunnel furnace at1200° C. for two hours. There was thus obtained the first component ofthe major ingredient in finely divided form.

Then we proceeded to the preparation of the second component, CaZrO₃, ofthe major ingredient of Test No. 1. We intermingled 448.96 grams ofcalcium carbonate (CaCo₃) and 551.04 grams of zirconium oxide (ZrO₂).Then we dried and pulverized the mixture and fired the resultingparticles in air at 1250° C. for two hours.

Then, in order to obtain the major ingredient of Test No. 1 in therequired molar ratio (0.98:0.02) of the first and second components, weintermingled 984.56 grams (98 mole parts ) of (Ba₀.99 Ca₀.03)O₁.02 TiO₂and 15.44 grams (two mole parts) of CaZrO₃. One thousand grams of themajor ingredient was thus obtained in finely divided form.

For the additives of Test No. 1 we first prepared the followingsubstances in the following amounts:

Li₂ O: 0.44 grams (1.0 mole part)

SiO₂ : 70.99 grams (80.0 mole parts)

BaCO₃ : 11.10 grams (3.8 mole parts)

CsCO₃ : 14.07 grams (9.5 mole parts)

MgO: 3.40 grams (5.7 mole parts)

To these substances we added 300 cubic centimeters of alcohol andstirred the resulting slurry for 10 hours in a polyethylene pot withalumna balls. Then we air fired the mixture at 1000° C. for two hours.Then we charged the fired mixture into an alumina pot together with 300cubic centimeters of water and pulverized it with alumina balls over aperiod of 15 hours. Then we dried the pulverized mixture at 150° C. forfour hours.

Thus we obtained in finely divided form the desired additive mixture ofone mole percent Li₂), 80 mole percent SiO₂ and 19 mole percent MO, withthe MO consisting of 3.8 mole percent BaO, 9.5 mole percent CaO and 5.7mole percent MgO. The relative proportions of BaO, CaO and MgO were 20,50 and 30 mole percent.

Having thus prepared the major ingredient and additive mixture of TestNo. 1, we added 20 grams (two weight parts) of the latter to 1000 grams(100 weight parts) of the former. Further, to this mixture, we added 15percent by weight of an organic binder and 50 percent by weight of waterwith respect to the total weight of the major ingredient and additives.The organic binder was an aqueous solution of acrylic ester polymer,glycerine, and condensed phosphate. Then we ball milled the mixture intoa slurry and then defoamed it in vacuum.

Then we charged the defoamed slurry into a reverse roll coater andshaped it into a thin, continuous strip on an elongate blacking strip ofpolyester film. Then we dried the strip by heating it to 100° C. on thebacking film. There was thus obtained a green ceramic strip with athickness of approximately 25 micrometers. We subsequently punched itinto "squares" sized 10 by 10 centimeters. These green ceramic squareswere to become the ceramic layers 12, FIG. 1, in the completed testcapacitors 10.

For the fabrication of the base metal film electrodes 14 on the ceramiclayers 12, we prepared 10 grams of nickel in finely divided form, withan average particle size of 1.5 micrometers, and a solution of 0.9 gramof ethyl cellulose in 9.1 grams of butyl "Carbitol" (trademark fordiethylene glycol monobutyl ether). We intimately intermingled them inan agitator for 10 hours, thereby providing an electroconductive paste.Then we "printed" the paste on one surface of each green ceramic square,which had been prepared as above stated, through a screen having anarray of 50 perforations of rectangular shape, each sized seven by 14millimeters.

After having allowed the printed paste to dry, we stacked two greensquares, with the printings thereon directed upwardly, and with theprintings on the two squares offset from each other to an extentapproximately half the pitch of the paste pattern in the longitudinaldirection. Then we placed the stack of two printed squares between twoseparate stacks of four unprinted squares each with a thickness of 60micrometers. Then we exerted a pressure of 40 tons on the resultingstack of printed and unprinted squares in their thickness direction at50° C., thereby firmly bonding them together. Then we cut the bondedsquares in a latticed pattern into 50 laminate chips of identicalconstruction.

We employed a furnace capable of atmosphere control for cofiring theabove prepared green dielectric bodies and, buried therein, theconductive layers which were to become the film electrodes 14 in thecompleted capacitors 10. We first air heated the chips to 600° C. at arate of 100° C. per hours, thereby driving off the organic binder thathad been used for providing the slurry of the powdered major ingredientand additives. Then we changed the furnace atmosphere from air to areductive (nonoxidative)atmosphere consisting of two percent by volumeof molecular hydrogen and 98 percent by volume of molecular nitrogen.Then, in this furnace atmosphere, we raised the furnace temperature from600° C. to 1150° C. at a rate of 100° C. per hours. We maintained forthree hours the maximum furnace temperature of 1150° C., at which theceramic bodies formulated in accordance with our invention were to besintered to maturity. Then we lowered the furnace temperature to 600° C.at a rate of 100° C. per hours. Then, with the furnace atmosphere againchanged to air (oxidative atmosphere), we maintained the temperature of600° C. for 30 minutes for the oxidizing heat treatment of the sinteredchips. Then we allowed the furnace temperature to drop to roomtemperature.

Thus we obtained the dielectric ceramic bodies 15 cosintered with thefilm electrodes 14 buried therein.

We proceeded to the production of the pair of conductive terminations 16on both sides of each ceramic body 15 at which were exposed the filmelectrodes 14. First, for the production of the inmost zinc layers 18,we coated both sides of each ceramic body 15 with an electroconductivepaste composed of zinc, glass frit and vehicle. Then, after havingallowed the coatings to dry, we heated them to 550° C. in air and heldthe temperature for 15 minutes, thereby completing the zinc layers 18each in direct contact with one of the two film electrodes 14. Then weformed the intermediate copper layers 20 over the zinc layers 18 byelectroless plating, and then the outermost solder layers 22 over thecopper layers 20 by electroplating an alloy of lead and tin.

We have thus completed the fabrication of the monolithic, multilayeredceramic test capacitors 10, each constructed as in FIG. 1, in accordancewith the ceramic composition of Test No. 1 of Table 1. The compositionof the ceramic bodies 15 of the thus completed capacitors 10 provedsubstantially akin to that before sintering.

As for the other ceramic compositions of Table 1, designated Tests No.2-75, we made similar capacitors through the same procedure as set forthin the foregoing in connection with the Test No. 1 composition, exceptfor the temperature of sintering in the reductive atmosphere, to whichwe will presently refer in more detail.

Then we tested all the capacitors of Tests Nos. 1-75 as to theirspecific dielectric constants, dielectric losses, resistivities, andcapacitance-temperature characteristics. We measured these electricalproperties of the test capacitors by the following methods:

Specific Dielectric Constant

The capacitance of each test capacitor was first measured at atemperature of 20° C., a frequency of one kilohertz, and an effectivevoltage of 1.0 volt. Then the specific dielectric constant was computedfrom the measured value of capacitance, and the area (25 squaremillimeters) of each of the opposed parts of the film electrodes 14, andthe thickness (0.02 millimeter) of that ceramic layer 12 whichintervenes between the film electrodes.

Dielectric Loss

The dielectric loss was measured under the same conditions as thespecific dielectric constant.

Resistivity

Resistance between the pair of conductive terminations 16 of each testcapacitor was measured after the application of a direct voltage of 100volts for one minute. Then the resistivity was computed from themeasured resistance value and the size of each test capacitor.

Temperature Dependence of Capacitance

The test capacitors were introduced into a thermostatic oven, and theircapacitances at various preselected temperatures were measured at afrequency of one kilohertz and an effective voltage of 1.0 volt. Thenthe percent changes of the capacitances at -55° and +125° C. from thoseat 25° C., and at -25° and +85° C. from those at 20° C., were computed.

Table 2 gives the properties of the test capacitors as measured by theabove described methods, as well as the maximum temperatures at whichthe test capacitors were sintered in the reductive atmosphere duringtheir manufacture.

                                      TABLE 2                                     __________________________________________________________________________    Firing Temperature & Capacitor Characteristics                                       Capacitor Characteristics                                                 Firing                                                                            Specific                                                                            Dielectric                                                       Test                                                                             Temp.                                                                             Dielectric                                                                          Loss  Resistivity                                                                          Capacitance Variations (%)                          No.                                                                              (°C.)                                                                      Constant                                                                            (%)   (megohm-cm)                                                                          At -55° C.                                                                   At 125° C.                                                                   At -25° C.                                                                   At 85° C.                  __________________________________________________________________________     1 1150                                                                              3560  1.1   3.0 × 10.sup.6                                                                 -11.2 +6.1  -6.7  -4.8                               2 1150                                                                              3610  1.1   3.3 × 10.sup.6                                                                 -10.3 +2.2  -5.8  -5.7                               3 1140                                                                              3620  1.2   2.8 × 10.sup.6                                                                 -11.7 +5.1  -7.3  -5.0                               4 1130                                                                              3580  1.1   2.6 × 10.sup.6                                                                 -12.3 +6.3  -8.4  -4.2                               5 1140                                                                              3530  1.3   2.3 × 10.sup.6                                                                 -11.4 +7.1  -6.3  -2.6                               6 1140                                                                              3600  1.2   2.7 × 10.sup.6                                                                 -11.0 +4.6  -6.0  -3.5                               7 1130                                                                              3640  1.2   2.9 × 10.sup.6                                                                 -11.6 +4.2  -6.5  -5.3                               8 1140                                                                              3550  1.2   2.2 × 10.sup.6                                                                 -11.2 +5.7  -6.3  -5.6                               9 1130                                                                              3530  1.2   2.4 × 10.sup.6                                                                 -12.0 +7.1  -7.2  -3.0                              10 1150                                                                              3490  1.2   2.6 × 10.sup.6                                                                 -11.2 +5.3  -6.6  -5.2                              11 1250                                                                              Not coherently bonded on firing                                        12 "   Not coherently bonded on firing                                        13 "   Not coherently bonded on firing                                        14 "   Not coherently bonded on firing                                        15 "   Not coherently bonded on firing                                        16 "   Not coherently bonded on firing                                        17 1140                                                                              3670  1.0   3.1 × 10.sup.6                                                                 -12.1 +6.8  -7.0  -3.4                              18 1130                                                                              3480  1.1   3.0 × 10.sup.6                                                                 -10.7 +5.1  -6.9  -4.1                              19 1130                                                                              3650  1.1   2.8 × 10.sup.6                                                                 -12.2 +6.3  -7.8  -4.8                              20 1140                                                                              3630  1.0   2.8 × 10.sup.6                                                                 -12.4 +6.2  -8.1  -4.2                              21 1140                                                                              3680  1.2   2.5 × 10.sup.6                                                                 -11.8 +5.1  -7.2  -4.3                              22 1140                                                                              3560  1.2   3.1 × 10.sup.6                                                                 -12.0 +6.1  -7.5  -4.6                              23 1140                                                                              3620  1.0   3.3 × 10.sup.6                                                                 -12.0 +6.0  -7.0  -4.7                              24 1250                                                                              Not coherently bonded on firing                                        25 1190                                                                              4040  1.6   1.3 × 10.sup.6                                                                 -11.9 +3.1  -7.5  -5.0                              26 1170                                                                              3840  1.2   1.7 × 10.sup.6                                                                 -12.3 +3.6  -7.8  -4.2                              27 1120                                                                              3260  1.0   2.6 × 10.sup.6                                                                 -13.0 +2.1  -8.4  -6.5                              28 1090                                                                              3080  1.5   1.9 × 10.sup.6                                                                 -14.0 +0.3  -8.8  -7.8                              29 1060                                                                              2690  1.7   1.5 × 10.sup.6                                                                 -18.3 -4.1  -10.6 -10.5                             30 1250                                                                              Not coherently bonded on firing                                        31 1180                                                                              4050  1.2   1.8 × 10.sup.6                                                                 -13.1 +6.3  -8.9  -2.7                              32 1160                                                                              3860  1.0   2.9 × 10.sup.6                                                                 -13.0 +7.0  -9.1  -2.2                              33 1140                                                                              3450  1.2   3.0 × 10.sup.6                                                                 - 13.8                                                                              +6.1  -8.5  -2.6                              34 1100                                                                              3060  1.5   2.6 × 10.sup.6                                                                 -14.2 +3.3  -8.8  -5.3                              35 1080                                                                              2810  1.7   2.6 × 10.sup.6                                                                 -20.3 -2.1  -11.0 -6.2                              36 1250                                                                              Not coherently bonded on firing                                        37 1160                                                                              4520  1.7   1.8 × 10.sup.6                                                                 -5.3  -7.2  -2.8  -8.8                              38 1150                                                                              3970  1.0   3.0 × 10.sup.6                                                                 -5.0  -7.3  -9.1  -9.2                              39 1100                                                                              3660  1.0   2.8 × 10.sup.6                                                                 -6.1  -8.4  -3.0  -9.2                              40 1070                                                                              3220  1.4   2.2 × 10.sup.6                                                                 -7.3  -11.3 -3.5  -9.6                              41 1040                                                                              2900  1.6   2.2 × 10.sup.6                                                                 -10.6 -13.0 -6.6  -11.0                             42 1130                                                                              3440  1.1   3.0 × 10.sup.6                                                                 -20.6 +11.6 -13.3 +5.3                              43 1100                                                                              3530  1.2   3.0 × 10.sup.6                                                                 -14.0 +6.1  -9.2  -1.7                              44 "   3600  1.0   2.8 × 10.sup.6                                                                 -12.3 +3.1  -7.5  -5.1                              45 "   3660  1.1   3.1 × 10.sup.6                                                                 -6.7  -1.8  -3.0  -9.0                              46 "   3590  1.1   3.3 × 10.sup.6                                                                 +1.2  -8.1  +0.1  -13.1                             47 1180                                                                              3650  1.1   3.5 × 10.sup.6                                                                 -18.3 +8.6  -11.6 +5.1                              48 1160                                                                              3820  1.0   3.8 × 10.sup.6                                                                 -14.0 +4.2  -9.3  -1.8                              49 1160                                                                              3730  1.1   4.0 × 10.sup.6                                                                 -9.2  -1.0  -3.4  -4.7                              50 1160                                                                              3810  1.2   3.5 × 10.sup.6                                                                 -3.8  -5.6  -1.9  -7.9                              51 1160                                                                              3840  1.1   3.3 × 10.sup.6                                                                 -0.3  -10.6 -0.2  -11.5                             52 1160                                                                              3670  1.7   1.6 × 10.sup.6                                                                 -17.1 +7.2  -11.5 +3.8                              53 1150                                                                              3880  1.2   3.0 × 10.sup.6                                                                 -13.5 +9.1  -8.5  +1.6                              54 1150                                                                              3880  1.1   2.5 × 10.sup.6                                                                 -12.6 +8.8  -7.4  -0.6                              55 1160                                                                              3630  1.0   2.4 × 10.sup.6                                                                 -11.8 +6.3  -6.5  -4.2                              56 1180                                                                              3530  1.1   3.3 × 10.sup.6                                                                 -11.2 +4.2  - 5.7 -8.3                              57 1180                                                                              3610  1.1   3.5 × 10.sup.6                                                                 -10.0 +2.1  -5.3  -8.8                              58 1180                                                                              3660  1.0   3.5 × 10.sup.6                                                                 -10.3 -3.1  -5.0  -11.2                             59 1180                                                                              3730  1.0   3.3 × 10.sup.6                                                                 -9.2  -4.6  -4.7  -11.5                             60 1140                                                                              3670  1.8   1.3 × 10.sup.6                                                                 -17.3 +12.6 -11.9 +6.3                              61 1130                                                                              3380  1.2   1.8 × 10.sup.6                                                                 -13.1 +7.5  -9.4  +3.1                              62 1130                                                                              3540  1.2   1.8 × 10.sup.6                                                                 -12.8 +5.1  -9.0  +3.6                              63 1150                                                                              3550  1.1   2.0 × 10.sup.6                                                                 -8.6  +3.0  -4.2  -5.1                              64 1150                                                                              3460  1.1   2.1 × 10.sup.6                                                                 -4.1  -2.8  -1.6  -9.0                              65 1150                                                                              3530  1.1   2.1 × 10.sup.6                                                                 -2.6  -4.1  -1.0  -11.0                             66 1120                                                                              3080  2.4   6.2 × 10.sup.4                                                                 -22.0 -10.3 -14.0 -7.4                              67 1140                                                                              3530  1.2   2.5 × 10.sup.6                                                                 -13.0 +5.8  -8.0  -6.2                              68 1160                                                                              3550  1.0   2.8 × 10.sup.6                                                                 - 11.2                                                                              +4.0  -7.0  -4.5                              69 1180                                                                              3380  1.0   2.9 × 10.sup.6                                                                 -10.5 +1.5  -5.3  -7.6                              70 1250                                                                              Not coherently bonded on firing                                        71 1120                                                                              3040  3.3   5.0 × 10.sup.4                                                                 -22.5 -11.1 -15.8 -11.3                             72 1130                                                                              3470  1.1   2.6 × 10.sup.6                                                                 -13.7 +6.2  -8.5  -4.4                              73 1150                                                                              3430  1.2   3.0 × 10.sup.6                                                                 -11.0 +3.0  -7.0  -5.5                              74 1180                                                                              3290  1.1   3.0 × 10.sup.6                                                                 -10.3 +1.0  -6.6  -7.1                              75 1250                                                                              Not coherently bonded on firing                                        __________________________________________________________________________

It will be noted from Table 2 that the specific dielectric constants ofthe Test No. 1 capacitors, for instance, averaged 3560, their dielectriclosses 1.1 percent, their resistivities 3.0×10⁶ megohm-centimeters, andtheir percent variations of capacitances from those at 25° C. to thoseat -55° and +125° C., -11.2 and +6.1 percent, and from those at 20° C.to those at -25° and +85° C., -6.7 and -4.8 percent, respectively.

Before proceeding further with the examination of Table 2, we willdetermine the criteria of acceptability for the four electricalproperties in question of the capacitors as follows:

Specific dielectric constant, at least 3000.

Dielectric loss, not more than 2.5 percent.

Resistivity, at least 1×10⁶ megohm-centimeters.

Temperature dependence of capacitance, within plus and minus 15 percentat -55° and +125° C., and within plus and minus 10 percent at -25° and+85° C.

A reconsideration of Table 2 in light of the above established criteriaof favorable capacitor characteristics will reveal that the capacitorsof Test Nos. 11-16, 24, 29, 30, 35, 36, 41, 42, 46, 47, 51, 52, 58, 59,60, 65, 66, 70, 71 and 75 do not meet these criteria. Accordingly, thecorresponding ceramic compositions of Table 1 fall outside the scope ofour invention. All the other test capacitors come up to these criteriaeven though they were sintered at temperatures of less than 1200° in areductive atmosphere.

Although Table 2 gives the percent variations of capacitances only at-55°, +125°, -25° and +85° C., we actually measured the capacitances atadditional temperatures of 0°, +20°, +25°, +40°, +60° and +105° C. Thecapacitance variations of all the test capacitors in accordance with ourinvention were within plus and minus 10 percent in the temperature rangeof -25° to +85° C. and within plus and minus 15 percent in thetemperature range of -55° to +125° C.

Now, let us study the ceramic compositions of Table 1 and thecorresponding capacitor characteristics of Table 2 in more detail. Theceramic compositions of Tests Nos. 24, 30 and 36 contained no additivespecified by our invention. The dielectric bodies formulated accordinglywere not coherently bonded on firing at a temperature as high as 1250°C. Consider the ceramic compositions of Tests Nos. 25, 31 and 37 forcomparison. They contained 0.2 par by weight of the additives withrespect to 100 parts by weight of the major ingredient. Even though thefiring temperatures for these test capacitors were as low as from 1160°to 1190° C., they possessed the desired electrical characteristics. Weset, therefore, the lower limit of the possible proportions of theadditives at 0.2 part by weight with respect to 100 parts by weight ofthe major ingredient.

The Test Nos. 29, 35 and 41 ceramic compositions contained as much asseven parts by weight of the additives with respect to 100 parts byweight of the major ingredient. The specific dielectric constants of theresulting capacitors are less than the above established criterion of3000. Also, their capacitance variations were outside the range of plusand minus 10 percent at -25° or +85° C. or outside the range of plus andminus 15 percent at -55° or +125° C. However, when the proportion of theadditives was reduced to five parts by weight as in Tests Nos. 28, 24and 40, the resulting capacitors had all the desired electricalcharacteristics. Accordingly, the upper limit of the possibleproportions of the additives is set at five parts by weight with respectgo 100 parts by weight of the major ingredient.

As for the major ingredient, (1-α){(Ba_(k-x) M_(x))O_(k) TiO₂ }+αCaZrO₃,we tested various values for α, k and x in order to determine desirableranges of such values. First of all, the value of x was set at zero inTests Nos. 52 and 60. In the resulting capacitors the capacitancevariation at -25° C. was outside the desired range of plus and minus 10percent, and the capacitance variation at -55° C. was also outside thedesired range of plus and minus 15 percent. However, all the desiredelectrical characteristics were obtained when the value of x was set at0.01 as in Tests Nos. 53, 54, 61 and 62. Thus we set the lowest possiblevalue of x at 0.01.

The Tests Nos. 58, 59 and 65 compositions had the value of x set at0.07. The capacitance variations of the resulting capacitors at +85° C.fell outside the desired range of plus and minus 10 percent. All thedesired electrical characteristics were obtained when the value of x wasset at 0.05 as in Tests Nos. 56, 57 and 64. The highest possible valueof x is therefore 0.05.

The capital M in the formula of the major ingredient represents eitheror both of Mg and Zn as aforesaid. The Tests indicate that the use ofeither or both of Mg and Zn does not substantially affect thecharacteristics of the resulting capacitors, and that the value of x canbe in the range of 0.01 to 0.05 in either case.

The value of α in the formula of the major ingredient was set at zero inTests Nos. 42 and 47. The capacitance variations of the resultingcapacitors fell outside the desired ranges at both -25° C. and -55° C.All the desired characteristics were met when the value of α was set at0.005 as in Tests Nos. 43 and 48. The lowest possible value of α istherefore 0.005.

The value 0.05 chosen for α in Tests Nos. 46 and 51 was too high becausethe capacitance variations of the resulting capacitors at 85° C. felloutside the desired range of plus and minus 10 percent. All the desiredcharacteristics were achieved when the value of α was set at 0.04 as inTests Nos. 45 and 50. The highest possible value of α is therefore 0.04.

When the value of k was set at 0.98 as in Tests Nos. 66 and 71, theresistivities of the resulting capacitors were both less than 1 ×10⁶megohm-centimeters. The capacitor characteristics were all satisfactorywhen the value of k was set at 1.00 as in Tests Nos. 67 and 72. Thelowest possible value of k is therefore 1.00.

When the value of k was set at 1.07 as in Tests Nos. 70 and 75, theresulting dielectric bodes were not coherently bonded on firing.Coherently bonded ceramic bodies were obtained, and the capacitorcharacteristics were all satisfactory, when the value of k was set at1.05 as in Tests Nos. 69 and 74. The upper limit of the possible valuesof k is therefore 1.05.

We have ascertained from the results of Table 2 that the acceptablerange of the relative proportions of Li₂ O), SiO₂ and MO, the additivesof the ceramic compositions in accordance with our invention, can bedefinitely stated in reference to the ternary diagram of FIG. 2. Thepoint A in the ternary diagram indicates the Test No. 1 additivecomposition of one mole percent Li₂ O, 80 mole percent SiO₂, and 19 molepercent MO. The point B indicates the Test No. 2 additive composition ofone mole percent Li₂ O, 39 mole percent SiO₂, and 60 mole percent MO.The point C indicates the Test No. 3 additive composition of 30 molepercent Li₂ O, 30 mole percent SiO₂, and 40 mole percent MO. The point Dindicates the Test No. 4 additive composition of 50 mole percent Li₂ O,50 mole percent SiO₂, and 0 mole percent MO. The point E indicates theTest No. 5 additive composition of 20 mole percent Li₂ O, 80 molepercent SiO₂, and 0 mole percent MO.

The relative proportions of the additives Li₂ O, SiO₂ and MO of theceramic compositions in accordance with out invention are within theregion bounded by the lines sequentially connecting the above definedpoints A, B, C, D and E in the ternary diagram of FIG. 2.

Tables 1 and 2 prove that the additive compositions within the abovedefined region makes possible the provision of capacitors of the desiredcharacteristics. The additive compositions of Tests Nos. 11-16 all falloutside that region, and the corresponding dielectric bodies were notcoherently bonded on firing at a temperature of as high as 1250° C. Theabove specified acceptable range of the relative proportions of theadditives holds true regardless of whether only one of BaO, MgO, ZnO,SrO and CaO is employed ad MO, as in tests Nos. 17-21, or two or more orall of them are employed as in the other Tests.

Although we have disclosed our invention in terms of specific Examplesthereof, we understand that our invention is not to be limited by theexact details of such disclosure but admits of a variety ofmodifications or alterations within the usual knowledge of theceramists, chemists or electricians without departing from the scope ofthe invention. The following, then, is a brief list of such possiblemodifications or alterations:

1. The low temperature sinterable ceramic compositions of our inventionmay contain various additives other than those disclosed herein. Anexample is a mineralizer such as manganese dioxide. Used in a proportion(preferably from 0.05 to 0.10 percent by weight) not adversely affectingthe desired characteristics of the resulting capacitors, the mineralizerwill serve to improve the sinterability of the ceramic compositions.

2. The start materials of the ceramic compositions in accordance withour invention may be substances such as oxides or hydroxides other thanthose employed in the foregoing Examples.

3. The temperature of the oxidizing heat treatment need not necessarilybe 600° C. but can be variously determined in a range (from 500° to1000° C. for the best results) not exceeding the temperature of thepreceding sintering in a nonoxidative atmosphere, the oxidizingtemperature being dependent upon factors such as the particular basemetal electrode material in use and the degree of oxidation required foreach ceramic material to be produced.

4. The temperature of cosintering in a nonoxidative atmosphere may alsobe changed in consideration of the particular electrode material in use.We recommend a range of 1050° to 1200° C. if the electrode material isnickel, as we have ascertained by experiment that little or noflocculation of the nickel particles takes place in that temperaturerange.

5. The dielectric bodies formulated in accordance with our invention,with or without electrodes buried therein or otherwise attached thereto,may be sintered in a neutral, instead of reductive, atmosphere.

6. The principles of our invention may be applied to capacitors otherthan those of the monolithic, multilayered configuration disclosedherein.

What we claim is:
 1. A solid dielectric capacitor comprising adielectric ceramic body and at least two electrodes in contacttherewith, the dielectric ceramic body consisting essentially of:(a) 100parts by weight of a major ingredient expressed by the formula,

    (1-α){Ba.sub.k-x M.sub.x)O.sub.k TiO.sub.2 }+αCaZrO.sub.3,

whereM is at least either of calcium and strontium; α is a numeral inthe range of 0.005 to 0.040; k is a numeral in the range of 1.00 to1.05; and x is a numeral in the range of 0.01 to 0.05; and (b) from 0.2to 5.0 parts by weight of an additive mixture of lithium oxide, silicondioxide and at least one metal oxide selected from the group consistingof barium oxide, strontium oxide, calcium oxide, magnesium oxide andzinc oxide, the relative proportions of lithium oxide, silicon dioxideand at least one selected metal oxide constituting the additive mixturebeing in that region of the ternary diagram of FIG. 2 attached heretowhich is bounded by lines sequentially connecting:the point A where theadditive mixture consists of one mole percent lithium oxide, 80 molepercent silicon dioxide, and 19 mole percent metal oxide; the point Bwhere the additive mixture consists of one mole percent lithium oxide,39 mole percent silicon dioxide, and 60 mole percent metal oxide; thepoint C where the additive mixture consists of 30 mole percent lithiumoxide, 30 mole percent silicon dioxide, and 40 mole percent metal oxide;the point D where the additive mixture consists of 50 mole percentlithium oxide, 50 mole percent silicon dioxide, and 0 mole percent metaloxide; and the point E where the additive mixture consists of 20 molepercent lithium oxide, 80 mole percent silicon dioxide, and 0 molepercent metal oxide.
 2. The solid dielectric capacitor of claim 1wherein the electrodes are buried in the dielectric ceramic body.
 3. Thesolid dielectric capacitor of claim 1 wherein the electrodes are of abase metal.
 4. The solid dielectric capacitor of claim 3 wherein thebase metal is nickel.
 5. A process for the manufacture of a soliddielectric capacitor which comprises:(a) providing in finely dividedform a mixture of:100 parts by weight of a major ingredient express bythe formula,

    (1-α){(Ba.sub.k-x M.sub.x)O.sub.k TiO.sub.2 }+αCaZrO.sub.3,

whereM is at least either of calcium and strontium; α is a numeral inthe range of 0.005 to 0.040; k is a numeral in the rang of 1.00 to 1.05;and x is a numeral in the range of 0.01 to 0.05; and from 0.2 to 5.0parts by weight of an additive mixture of lithium oxide, silicon dioxideand at least one metal oxide selected from the group consisting ofbarium oxide, strontium oxide, calcium oxide, magnesium oxide and zincoxide, the relative proportions of lithium oxide, silicon dioxide and atleast one selected metal oxide constituting the additive mixture beingin that region of the ternary diagram of FIG. 2 attached hereto which isbounded by lines sequentially connecting: the point A where the additivemixture consists of one mole percent lithium oxide, 80 mole percentsilicon dioxide, and 19 mole percent metal oxide; the point B where theadditive mixture consists of one mole percent lithium oxide, 39 molepercent silicon dioxide, and 60 mole percent metal oxide; the point Cwhere the additive mixture consists of 30 mole percent lithium oxide, 30mole percent silicon dioxide, and 40 mole percent metal oxide; the pointD where the additive mixture consists of 50 mole percent lithium oxide,50 mole percent silicon dioxide, and 0 mole percent metal oxide; and thepoint E where the additive mixture consists of 20 mole percent lithiumoxide, 80 mole percent silicon dioxide, and 0 mole percent metal oxide;and (b) molding the mixture into desired shape and size, the moldinghaving at least two electrode portions of an electroconductive material;(c) cosintering the molding and the electrode portions to maturity in anonoxidative atmosphere; and (d) reheating the cosintered molding andelectrode portions in an oxidative atmosphere.
 6. The process of claim 5wherein the electrode portions are formed on the molding by coating thesame with an electroconductive paste composed principally of a basemetal.
 7. The process of claim 6 wherein the base metal is nickel. 8.The process of claim 5 wherein the molding and the electrode portionsare cosintered in a temperature range of 1050° to 1200° C.
 9. Theprocess of claim 5 wherein the cosintered molding and electrode portionsare reheated in a temperature range of 500° to 1000° C.